Improved turn-table for bridges



UNITED STATES PATENTA OFFICE.

NILLIAM SELLERS 85 OO., OF SAME PLAGE.

IIVIPROVED TURN-TABLE FOR BRIDGES.

Specification forming part of Letters Patent No. 64,713, dated May 14, 1867.

To all whom it may concern:

Be it known that I, COLEMAN SELLERS, of the city and county of Philadelphia, in the State of Pennsylvania, have invented a new and useful Improvement in Turn-Tables for Pivot-Bridges.

In pivot-bridges, as heretofore made, the revolving portion of the structure is usually supported partly upon a central pivot and partly upon a circular track, which is supported upon wheels resting and revolving upon a similar track sustained by the pier. In some cases the whole weight is transferred to the central pivot, the circular track being used only to prevent the superstructure from tipping over. Whenever it has been attempted to distribute the load upon the circular track and the pivot at the same time it has been found impracticable to obtain sufficient accuracy in the track to prevent one or the other support from taking more than its share of the load in the different positions it assumes-in revolving, thus causing it to work very hard and unequally 5 and when ithas been attempted to transfer the whole load to the pivot, a transverse beam has been used which is sufficiently strong to sustain the load upon its extremities and transfer it to the center. But as in all cases the circular track is a necessity for preventing the tipping of the revolving structure, it is found very difficult to combine this beam and track so as to make a sufficiently strong connection with the bridge, and at the same time to prevent the wheels upon which the circular track rests to revolve freely between the tracks without obstruction from the beam.

The nature of my invention consists in supporting the revolving portion of the bridge upon a platform or its equivalent which shall have sufficient stiffness to resist the radial strain of the diagonal bolts which I use to transfer the load from the platform to a central support, resting or turning on a pivot or its equivalent.

In order that my invention may be fully understood, I will now proceed to'describe its construct-ion and operation, reference being made to the accompanying drawings, making part of this specification, in which- Figurc l is a plan, Fig. 2, an elevation, partially in section, similar letters on each referring to similar parts.

The platform upon which I sustain the turning portion of the bridge, or, as it is usually called, the draw, can be made of either metal or wood. I shall describe it as made in the simplest form of iron. It consists of a cylindrical curb, X, formed of an upper castiron curb, A, and lower cast-iron curb, B, united by wrought-iron plates C C, thus forming a powerful compound beam, curved into the form of a cylinder. Between the lower curb, B, and a circula-r track, D, on the pier is a series of wheels, E. These wheels E are held in position by means of bands of iron F F, through which their axles pass, and are secured by nuts. An elongation, G, of the axles extends radially inward to a band, H, surrounding and revolving freely on the base of the center-post I, thus guiding the wheels E on the track D. The upper, A, and lower cord, B, are arranged with diagonal bolt-holes, through which pass radial bolts K L. These radial bolts unite the bottom chord, B, to the top of a center cylindrical casting, M, and the radial bolts L unite the top chord, A, to the bottom of the same casting M. The cylindrical casting M is suspended by bolts n a under a cap, O, the cap O resting and turning on the post I. Between the cap O and casting M is a space, P, iilled with wood, as a packing. By adjusting the thickness of this wood the bolts a n can lift cylinder M, and with it, through the bolts K, raise uniformly the whole platform upon which the bridge rests. The platform is thus formed of a stiff curb, held in place and made one with the central casting, M, by means of the radial diagonal bolt K L.

Now, it must be evident to any intelligent mechanic that the platform may be made of timber framed as a polygon, each side being formed of a short truss-beam, with stout posts at the angle of the polygon, the diagonal bolts K L passing from top and bottom of each post to the center cylinder, M, a circular metal track being bolted to the under side of the framed platform, the theory of my invention consisting in the use of a platform of sufficient stiffness to resist the strain of the radial diagonal bolts, and thus to transfer the load to the central casting, M; and many modifications may be The combination of the centralcylinder", M, made in form of the parts, depending upon the radial bolts K and L, and the cylindrical curb material, and in the construction as Well as in X or its equivalent, substantially as described, the nature, of the bridge-structure resting on for the purpose specified.

the platform, Without affecting the theory of application. COLEMAN SELLERS.

I do not, therefore, limit my cla-im to the precise form and arrangement of parts as de- XVitnesses: J scribed; but WILLIAM: HOWARD,

What I claim as new, and desire to secure HARRY STEWART.

by Letters Patent, isf- 

